This invention relates to a composition which is a mixture of compounds useful in the preparation of a coating on polymeric substrates in order to enhance adhesion between the substrate and a subsequently applied polymeric coating. The composition is specifically useful to coat polyester yarn or cord so that it will bond better to the subsequently applied elastomeric compound.
In the elastomer reinforcing art, adhesives are used for bonding both polyester and nylon to elastomer. A coating composition is applied and cured by heating usually as part of a hot stretching operation. A conventional coating composition is an aqueous solution of Resorcinol-Formaldehyde and a Latex of a copolymer of butadiene, styrene and a vinyl pyridiene known as "RFL" adhesive.
In polyester cord reinforcement of elastomers, the art has developed the further refinement of first coating the substrate polyester with a subcoat. An organic solvent solution of a diisocyanate or a triisocyanate has been used as a subcoat, which is later coated with the "RFL" adhesive--U.S. Pat. No. 2,990,313 to Knowles. Also see U.S. Pat. No. 2,994,671 which shows phenol "blocked" isocyanates used in this manner; and U.S. Pat. No. 3,179,547 to Kigane et al. which shows ethylene imine blocked isocyanates used in this manner. Currently available in the market is toluene 2,4-diisocyanate, that has been reacted with trimethylol propane at the para position and "blocked" with phenol at the ortho position. This compound is recommended for use in subcoating polyester yarn and cord to be subsequently treated with RFL adhesive and then used to reinforce elastomers.